I think that Thai Airways also is a good alternative. It is very easy to get Silver (only 10.000 miles) and also Gold (50.000 in one year or 80.000 over two consecutive years). You also keep your status for two years instead of one which is typical.

Thai doesn’t have different levels of Gold, so once you have their Gold you are entitled to all the privileges of Gold of the other carriers as well. We frequently fly on short notice or on fully booked flights and experienced these advantages many times already. Advantages like priority on waiting lists, no problems with overbooked flights etc. This also holds for non Thai flights.

I also experienced that I always get the requested upgrades or free flights from my local Thai office, which is certainly not the case for all carriers. It must be said on the other hand that we both fly almost 75% of this distance with Thai; we live in Europe and have a second home in Thailand.

Hendrik